The sleeves are sealed in the masonry with a slight slope towards the outside (fixed sleeve Ø D2 on the outside of the wall and adjusting sleeve Ø D1 on the inside).
Provide an overlap of at least 20 mm between the 2 sleeves and an overhang of the sleeve on the inside of 30 mm minimum for the connection of the duct.
The aluminum grille simply clips onto the sleeve on the outside.
